Fluid pumps, particularly hydraulic oil pumps for actuating vehicle repair equipment are well known. The hydraulic pumping unit of the present invention is designed to provide a unit of greater efficiency in operation when driven by conventional mechanisms such as air motors and electric motors or the like. A dependable unit therefore is provided having a reduced cost and improved efficiencies as a result of a relatively simple design wherein some of the parts provide multiple functions.
It is well known to provide a working module including a pump driven by an air motor or an electric motor. Examples exist in the prior art of such devices. One such device manufactured by Chart Industries is illustrated in FIG. 1 and includes a pump having inlet ports for hydraulic oil and outlet ports. The inlet ports provide a path for oil to enter the valve from a hydraulic fluid reservoir through a dedicated inlet port having a ball check valve located therein to allow hydraulic fluid to enter but not exit the pump during the intake stroke of the two-cycle pump. The pump is driven by an air motor which includes a piston driven by compressed air to drive the piston from top-dead center which is defined in this case adjacent the end of the pump near the hydraulic fluid reservoir to bottom-dead center remote that end. As the intake stroke begins, oil enters the pump through the dedicated inlet port drawing oil into the pump until such time as the piston reaches bottom-dead center and is pushed by the air motor as dictated by the operator as the appropriate switch is operated to drive the piston toward top-dead center compressing the oil and having the oil pass through the outlet port toward a hydraulic cylinder to be utilized, for example, to straighten the frame of an automobile. This is not part of the invention and will not be discussed any further. The air motor may be substituted by an electric motor as is well known in the art. The operation of the air motor is not discussed any further except to define it as a reciprocating air motor to drive the hydraulic piston between top-dead center and bottom-dead center. Once the work is completed by the remote hydraulic cylinder, it is necessary to return the fluid to the hydraulic reservoir and allow the hydraulic cylinder to return to its inoperative position. To do so, a separate air-operated valve is required which drives a piston forward as dictated by the operation of another control by the operator to lift the check from its seat in an opposite direction from the check's normal use and to allow hydraulic fluid to flow back into the pump and then back into the hydraulic fluid reservoir through a separate release mechanism and port.
Such an operation is therefore required of the pump having dedicated return lines and inlet ports as well as return ports are necessary. With such a pump, pressures in the order of 10,000 psi at the outlet may be generated. However, the costs of manufacturing required to produce such a pump are relatively high in that the pump must be manufactured of operable components which are ultimately assembled. This prior art pump manufactured by Chart Industries at the present time has dedicated ports each of which require a predetermined amount of space-defining channels. These dedicated channels or ports create the disadvantage of pockets of turbulence when the reciprocal piston moves between the pressure stroke and the intake stroke. The intake port interferes with the build up of pressure at top-dead center position and inhibits the capability of the pump to generate higher pressures. Further, if oil is not made quickly available to the pump at these higher pressures, cavitation will result.
Nowhere within the prior art is there found a pump design which eliminates the need for dedicated ports and the associated check valves provided therewith and provides a pump construction that utilizes an existing channel and port in multiple-use fashion allowing hydraulic fluid to enter the pump without a check on that particular intake function and which in the elimination of an intake check and port and hoses required, elbows and the like, thereby would reduce the pressure drop across that port. Further, it would be advantageous to provide flow back to the hydraulic fluid reservoir from an operating unit such as a cylinder. It would be advantageous to provide the fluid flowing back through an outlet port and through chambers within the port construction of the valve including a ring chamber adjacent to the inlet port for allowing fluid to flow back to the hydraulic reservoir from the cylinder through the ring-shaped chamber and the inlet port as the piston moves to bottom-dead center closest to an air motor.
It is therefore a primary object of the invention to provide a high-pressure two-cycle hydraulic pump which is cost effective to manufacture and easy to manufacture.
It is a further object of the invention to provide a high-pressure hydraulic two-cycle pump made from a solid cylinder of metal which is easily machined to provide all necessary ports therein.
It is a further object of the invention to improve the efficiency in high-pressure hydraulic two-cycle pumps by simplifying the construction thereof.
It is a further object of the invention to provide such a high-pressure pump assembly embodied in a working module utilized to straighten frames of vehicles.
Further and other objects of the invention will become apparent to those skilled in the art when considering the following summary of the invention and the more detailed description of the preferred embodiments illustrated herein.